Electrostatic and Hydrogen Bond Immobilization of Trypsine onto pH-Sensitive N-Vinylpyrrolidone and 4-Vinylpyridine Radical co-Grafted Chitosan Based on Hydrogel

摘要

The present investigation of new hydrogel based on chitosan was prepared by radical graft copolymerization of N-vinylpyrrolidone and 4-vinylpyridine with chitosan and cross-linking by N, N '-methylen-bis-acrylamide. The swelling behavior of the prepared hydrogel, with the optimal amount of gelator, was investigated. The hydrophilicity, and pH sensitivity of gel was suitable for trypsin carry. Trypsin was loaded onto the hydrogel enternal pores and surfaces by electrostatic interaction and hydrogen bond attachment. Several parameters, such as adsorbtion of pH value, loading time, and buffer solution concentration on trypsin loading amount, also enzyme activity were examined. According to the kinetic and FTIR, SEM spectroscopy analysis data trypsin was combination by the hydrogen bond and electrostatic interaction to the chitosan based structure. The hydrogen bonds were formed between -NH2, -CH2OH, >C=O, pyridine ring, -OH, and -NH- groups of carrier with -NH2, -COOH, -OH, >C=O, -NH-, disulfide bridge, ester groups of trypsine. In additional, at pH=5-8, the functional groups in the gel are partially ionized and take the form of -NH3+, -OH2+, >COH+. The protein is the same degree ionized in that medium, and the protein interacts electrostatically with the carrier.